A gas turbine engine typically comprises a multi-stage compressor that takes air, which has been drawn into the engine, and compresses it into a higher pressure and temperature. A majority of this air passes to the combustion system, which mixes the compressed and heated air with fuel and contains the resulting reaction that generates the hot combustion gases. These gases then pass through a multi-stage turbine, which, in turn drives the compressor, and possibly a shaft of an electrical generator. Exhaust from the turbine can also be channeled to provide thrust for propulsion of a vehicle.
Typical compressors and turbines comprise a plurality of alternating rows of rotating and stationary airfoils. The stationary airfoils, or vanes, direct the flow of air in a compressor or hot combustion gases in a turbine onto a subsequent row of rotating airfoils, or blades, at the proper orientation in order to maximize the output of the compressor or turbine. The performance of the gas turbine engine is dependent on the mass of air entering the engine. Generally, the greater the amount of air that enters the engine, the more power that is produced.